The invention relates generally to improvements in grand piano actions and more specifically to an assembly which replaces the knuckle on the hammer shank and reduces unwanted friction.
The modern conventional grand piano action is one of the oldest inventions in current and common use today. In fact, the basic grand piano action has undergone only minor revisions since it introduction over a century ago.
One area that has attracted parties attempting to improve the grand piano action relates to the knuckle, that is, the component disposed intermediate the repetition lever and the hammer shank which transfers energy therebetween. Specifically, attention has been directed to what is referred to as knuckle friction. The knuckle and the friction it generates has only one purpose: to effect a smooth transition in hammer support from the back check to hammer support by the repetition lever. This occurs only after the key has fully descended and the piano action has just begun its return to a quiescent state. Knuckle friction absorbs energy from the repetition lever as it suddenly applies lift to the knuckle and begins to lift the hammer shank and hammer. This prevents the hammer from jumping upward when released by the back check. A jumping hammer is perceived by the performer as a slight yet distracting jolt to the finger. Once the change in hammer support occurs knuckle friction is of no further value. Nonetheless, knuckle friction still exists.
Various improvements to piano actions have been proposed. For example, U.S. Pat. No. 106,396 teaches a piano action have an under-hammer disposed generally parallel to the hammer shank when it is at rest. The under-hammer includes an enlarged head which is acted upon by a moveable portion of the jack and which in turn contacts the portion of the hammer shank near its pivot.
U.S. Pat. No. 424,202 is intended to prevent wear upon the knuckle of the hammer shank by the jack. In this device, a pivoted finger is interposed between the repeating lever and the hammer shank. At rest, the finger is disposed parallel to the repetition lever but it is pivoted to the rider flange. The free end of the finger is acted upon by the repetition lever on one side and acts upon a knuckle secured to the hammer shank.
U.S. Pat. No. 520,989 teaches a similar finger or lever which is disposed parallel to the repetition lever and which is also pivotally secured thereto. This patent also discloses the use of a regulating screw to adjust the tension of a spring providing bias to the repetition lever.
Finally, U.S. Pat. No. 1,206,509 also teaches a grand piano action having an intermediate finger disposed generally parallel to the repetition lever and pivotally secured thereto. The finger is capable of slight independent movement with respect to the repetition lever.
The foregoing review of patents reveals attention directed to the problem of knuckle friction. The foregoing review also suggests that further improvements in grand piano actions relating to knuckle friction are both desirable and possible.